Police boats combed the banks of the Potomac River on Friday, slowly scanning the shoreline in the rain as investigators sought clues into the midair collision that killed 67 people and raised questions about air traffic safety around the nation’s capital. The black box from the Army Black Hawk helicopter that collided with a commercial jetliner and crashed into the Potomac River has been recovered, investigators announced. They are reviewing that flight data recorder along with two recovered earlier from the jet. No one survived the Wednesday night collision. The remains of 41 people had been pulled from the river as of Friday afternoon, including 28 that had been positively identified, Washington, D.C., Fire Chief John Donnelly Sr. said at a news conference. He said next of kin notifications had been made to 18 families, and he expects all the remains to be recovered. MORE: https://www.wthr.com/article/news/nation-world/midair-collision-kills-67-people-deadliest-us-air-disaster-in-decades/507-3e711c59-52a5-4337-b3f4-be317368d9e8